Demographic and Treatment Variables Influencing Outcome for Localized Paratesticular Rhabdomyosarcoma: Results from a Pooled-Analysis of North American and European Cooperative Groups

Walterhouse D, Barkauskas D, Hall D, Ferrari A, De Salvo GL, Koscielniak E, Stevens M, Martelli H, Seitz G, Rodeberg D, Shnorhavorian M, Dasgupta R, Breneman JC, Anderson JR, Bergeron C, Bisogno G, Meyer WH, Hawkins D, Minard-Colin V. J Clin Oncol. 2018 Oct 23:JCO2018789388. DOI: 10.1200/JCO.2018.78.9388.

Treatment recommendations for localized paratesticular rhabdomyosarcoma (PT RMS) differ in North America and Europe. We conducted a pooled analysis to identify demographic features and treatment choices that affect outcome.

Patients and Methods
We retrospectively analyzed the effect of nine demographic variables and four treatment choices on event-free survival (EFS) and overall survival (OS) from 12 studies conducted by five cooperative groups.

Eight hundred forty-two patients with localized PT RMS who enrolled from 1988 to 2013 were included. Patients age ≥ 10 years were more likely than younger patients to have tumors that were > 5 cm, enlarged nodes (N1), or pathologically involved nodes (P ≤ .05 each). With a median follow-up of 7.5 years, Kaplan-Meier estimates for 5-year EFS and OS were 87.7% and 94.8%, respectively. Of demographic variables, cooperative group, era of enrollment, age category, tumor size, Intergroup Rhabdomyosarcoma Study group, and T stage affected EFS (P ≤ .05 each). Surgical assessment of regional nodes, which was performed in 23.5% of patients—usually in those age ≥ 10 years or with suspicious or N1 nodes—was the only treatment variable associated with EFS by univariable and multivariable analyses (P ≤ .05 each) in patients age ≥ 1 year. A variable selection procedure on a proportional hazards regression model selected era of enrollment, age, tumor size, and surgical assessment of regional nodes as significant (P ≤ .05 each) in the EFS model, and era of enrollment, age, tumor size, and histology (P ≤ .05 each) in the OS model.

Localized PT RMS has a favorable prognosis. Age ≥ 10 years at diagnosis and tumor size larger than 5 cm are unfavorable prognostic features. Surgical assessment of regional nodes is important in patients age ≥ 10 years and in those with N1 nodes as it affects EFS.